What is 5m 6mn-(-9n) 2(m-n)?

To simplify the expression ( 5m + 6mn - (-9n) + 2(m - n) ), first, we can rewrite it as ( 5m + 6mn + 9n + 2m - 2n ). Next, we combine like terms: ( (5m + 2m) + 6mn + (9n - 2n) ), which results in ( 7m + 6mn + 7n ). Thus, the simplified expression is ( 7m + 6mn + 7n ).